Worlds of David Darling

Encyclopedia of Science

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Encyclopedia of Alternative Energy and Sustainable Living

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Remembering the launch of Voyager 2, August 20, 1977

Launhh of Voyager 2

Exactly 37 years ago today as I write this, a Titan-Centaur blasted off from Cape Canaveral carrying NASA's Voyager spacecraft on the first leg of its journey to the stars. Over the coming years, Voyager 2 would fly past all four gas giants of the Solar system, Jupiter, Saturn, Uranus, and Neptune, before heading out on an exit trajectory for interstellar space. Today, it continues to send backtscientific data and will do so until its nuclear batteries run dry.

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Rosetta doing triangles around a bizarre-shaped object

comet 67Partwork of alien spaceship
Comet 67P looks like a giant battered bone – or, from some angles, even a derelict spaceship!

The European Space Agency probe Rosetta is now safely in orbit around Comet 67P/Churyumov-Gerasimenko – although 'orbit' isn't quite the right word for how it's moving at the moment. Rosetta is actually traveling in a triangular path around 67P, firing its thrusters at the rounded corners in order to maintain a distance of about 100 km from its target. By measuring how much the thrusters have to be fired to make these maneuvers, mission controllers are figuring out the gravity pull of te comet so that eventually the spacecraft can be put into a small, stable orbit.

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The dinosaurs might have survived – and then what?

A new study concludes that the dinosaurs were killed off about 65 million years ago by a perfect storm of events, including rising sea-levels and massive volcanic activity. If the asteroid impact that applied the coup de grace had arrived a few million years earlier or later than it did, the researchers suggest, the dinosauts may have been in better shape, in terms of their diversity, to survive. They would then have continued to evolve and adapt to changing conditions, and perhaps even have survived to the present day. How smart might they have become, and what might they have looked like?

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Coast to Coast AM, July 23

Coast to Coast AM

Been about a year since I was on Coast to Coast AM radio so it was great to be back, talking this time about the dangers of near-Earth asteroids and solar flares, that strange crater found recently in Siberia, and the prospects for finding alien life and intelligence. Thanks to everyone who tuned in.

Read more (Coast to Coast AM)


The mysterious crater of Yamal

Yamal crater

This 80-meter wide crater appeared recently in the Yamal peninsula of northern Siberia. What caused it is still unknown, although a few theories are kicking around. It certainly isn't a meteorite or asteroid crater because any kind of high-energy collision wouldn't leave such a hole in the middle. The presence of debris around it also rules out the possibility of it being a sinkhole. One credible explanation is that it formed from the collapse of a soil covered dome of ice called a pingo. More worrying is that it may have resulted from underground methane violently bursting to the surface when the overlying permafrost was weakened due to rising temperatures. If climate change is to blame, this spectacular feature could be the first of many to open up, releasing vast quantities of methane – a potent greenhouse gas– into the atmosphere.

Read more (The Guardian)

The asteroids we need to be most concerned about

Asteroid exploding over Russia

The small asteroid that exploded over Russia last year and caused widespread structural damage served as a wake-up call. Despite all our efforts to keep track of space rocks that might threaten the Earth, some potentially devastating ones can still slip through the net undetected. Astronomers have devised a few different ways to categorize asteroids (and comets) that could pose a threat to us over the next few tens or hundreds of years. One of these measures of 'potentially hazardous objects' is known as the Palermo Technical Impact Hazard Scale. It takes into account both the size of the object and the chance of it hitting us. Topping the Palermo Scale at the moment is an asteroid called 2009 FD. A few asteroids are rated as having a higher chance of hitting us over the next century or so, but 2009 FD comes top of the list because it's also pretty big – almost half a kilometer across – so if it did hit us, depending on where it hit us, it could cause widepread devastation and loss of life.

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The habitable planet that never was

Artist's impression of Gliese 581g and its star

It was the first Earth-like habitable planet to be found: a world about three times as massive as our own, rocky, and right in the middle of its stars habitable zone. For several years, Gliese 581g, discovered in 2010, topped the league table of exoplanets most likely to host life. The trouble is: it doesn't exist. That's the conclusion of a study just published by a research team using two powerful ground-based spectrographs, ESO HARPS and Keck HIRES. Both Gliese 581g and its supposed companion planet 581d are not real worlds at all but features due to magnetic activity on the star as its span around.

Read more (Penn Satte University)

The universe's biggest cold spot may be linked to the biggest cosmic void

cold spot in the cosmic microwave background

Astronomers have known for a few years about a 'cold spot' in the cosmic microwave background – a patch in the sky where the afterglow of the Big Bang is cooler than in other directions. There have been a few theories kicking around to try to explain this curious feature, including the intriguing one that it might be a place where another universe has bumped into ours. But perhaps there's a more mundane (if that's the right word!) explanation: one that involves the biggest known void in the universe.

Read more (New Scientist)

What if light is not as fast as we thought?

Supernova 1987A

Supernova 1987A
If physicist James Franson of the University of Maryland is right, the speed of light may be slower than the value normally accepted – 299,792,458 meters per second. His suggestion comes from observations of supernova SN 1987A. Both neutrinos and photons were detected on Earth coming from the blast. But scientists were puzzled to find that the photons arrived 4.7 hours later than expected. At the time, this was put down to the possibility that the photons came from another source. But Franson has offered another theory: namely, that photons from the explosion split many times into electrons and positrons during their passage to Earth before, each time, recombining back into photons. Such splitting, he reasoned, would lead to a gravitational differential between the electrons and positrons, and a minute energy impact when they recombined — enough to result in a tiny slowdown during travel.

Read more (Physorg)

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